at the moment i build a computer for gaming on pure value i have a new 600W corsair PSU on the way but i also have an AMD phenom ii 840 x4 processor at 3.2 Ghz and 8 GB of kinston value ram so not very high speed, which would give me a better performance upgrade, new corsair vengeance RAM or getting one of the new FX processors, my mobo is AM3 compatible with 4 RAM slots and 1 PCIE with a GTX 560

Last time I saw a benchmark on RAM speed's vs FPS in games the differences were 2-3FPS per 200MHz increase on RAM. So 1333MHz vs 1866MHz would give you mabye 6-8FPS more.
 
It highly depends on the games you play and how they run. Some are GPU dependant and some are more CPU dependant. It also highly depends on what resolution you play at. The lower the resolution (around 720p), Intel processors blow away AMD and it's woth the switch. But at higher resolutions, it's better to go with something like the FX-6100.
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103962
 
I'm not sure if you will actually see that much of a difference in your games though... Since you are only running a GTX 560. Not going to be dealing with a huge bottleneck or anything unless you go SLI (which you can't) or get something like a GTX 670 or above.
 
 

FX-6100 to FX-8150  (If you are going just on value and only going to game the FX-4170 hands down.)
GTX 670 (2GB) or 7870 (2GB)
7-8-8-24 / 2 x 4 GB DDR3 1600 MHz (8GB) or 8-9-9-24 / 2 x 4 GB DDR3 1866 (8 GB)
970 or 990X chipset
My recommendation
 
FX-4170 benchmarks:
http://img442.imageshack...mg442/2839/amdbench.png <-- test bench info
http://img444.imageshack....444/4991/amdbench1.png <-- full detail 1080p Crysis (1) (FPS)
http://img341.imageshack....341/8660/amdbench2.png <-- full detail 1080p Resident Evil (5) (TPS)
http://img225.imageshack....225/7641/amdbench3.png <-- fulll detail 1080p Street Fighter (4) (Any other genre)
 
Also, if you can wait like me (Phenom II X4 965 BE)
I recommend waiting for
FX-4320 (I don't do just gaming so I am waiting for the FX-8350)
670 2GB to get cheaper over time
7-7-7-21 DDR3 1600 MHz so you can throw down a couple sticks in every DIMM/(1866 you are limited to two slots till you enter the "OC/No Warranty" spec.
1070 or 1090X for full native USB 3.0 and new 45-nm NB/SB(aka faster SATA/stable PCI-E).

Thanks guys, however in all this i can still only afford to get either processor or RAM which would give me the best performance for money, i am not sure how much of a difference cache makes on a processor and the phenom ii 840 has a small cache :(

I also vote for the FX 4170

FX 4170 without a doubt.  Upgrading the RAM won't yield much noticable difference. 

Eh, I don't see a need for the upgrade in your situation. You'll be fine... 
 
If money is tight I highly suggest visiting the EVGA Marketplace to check for people selling their used hardware. You can usually get a pretty good deal.
 
I don't know if you have access or not, but you have enough posts to apply for it. You just contact Shane for access.

what difference would i see between the fx6100 and the fx4170 ? i would have thought 6 cores would be better than 4 even if speed is a slight sacrifice

willmono7
what difference would i see between the fx6100 and the fx4170 ? i would have thought 6 cores would be better than 4 even if speed is a slight sacrifice.

You wouldn't see a big difference if you were just playing a game.  The difference when you add something with that game like capturing...via Dxtory, Fraps, Bandicam.  Other than that you wouldn't really notice the difference between the FX-6100 from the FX-4170 if you were gaming + recording.  There are other workloads that benefit from six-cores and that is rendering/compressing the footage from the capture...
 
If you want to do a lot of workloads at the same time and want to have short times in completing multithreaded tasks: (Best to worst)
 
FX-8350 > FX-8150 > FX-8120 > FX-6300 > FX-6200 > FX-6100 > FX-4320 > FX-4170 > FX-4100
 
Best just Gaming:
FX-4320 > FX-6300 > FX-4170 > FX-6200 >  FX-6100 > FX-4100 > FX-8120 > FX-8150 > FX-8350

Thankyou, i would love to do recording and at the moment my phenom 2 is not up for it, so i might invest in a 6 core